Characterization of the Bag Breakup of Liquid Drop Using High-Speed Digital In-Line Holography

2018 ◽  
Author(s):  
Longchao Yao ◽  
Jun Chen ◽  
Paul E. Sojka ◽  
Xuecheng Wu
Keyword(s):  
High Speed ◽  
Liquid Drop ◽  
Early Stage ◽  
Diagnostic Technique ◽  
Turbine Engines ◽  
Thin Wall ◽  
Gas Turbine Engines ◽  
Secondary Droplets ◽  
The Relationship

Quantifying the early stage of bag-type breakup of droplet is an important way to study the mechanism of drop breakup, but remains a challenge due to the lack of spatial-temporal resolved diagnostic technique. High-speed digital in-line holography at 20 kHz is employed to characterize secondary droplets formed in bag rupture of an ethanol drop exposed in the gas stream. Droplets as small as 10 μm are resolved at the beginning of bag rupture at Weber number of 11. The velocities of secondary droplets can almost reach that of the gas stream. Then the thin wall shrinks to form wrinkles that will generate relatively larger secondary droplets with smaller velocities. Droplet diameters are statistically displayed and the relationship between velocity and diameter as well as time is analyzed. This will help the further understanding of fuel spray generation in gas turbine engines.

Renovation features of powder high-speed steels broaches with plazma hardening

2021 ◽  
pp. 82-85
Author(s):  
A.S. Politov ◽  
R.R. Latypov
Keyword(s):  
Gas Turbine ◽  
Comparative Studies ◽  
High Speed ◽  
Atmospheric Plasma ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Cold Atmospheric Plasma ◽  
Plasma Hardening

The comparative studies results of the durability of cutting properties of new and restored by regrinding and repeated plasma hardening with the application of multi-layer Si—O—C—N nanocoating system (PECVD by cold atmospheric plasma) powder high — speed steels broaches teeth for the processing of hard-to-process materials profilecomposite gas-turbine engines components are presented.

Review of Metrics and Assignment of Confidence Intervals for Health Management of Gas Turbine Engines

2008 ◽  
Author(s):  
Craig R. Davison ◽  
Jeff W. Bird
Keyword(s):  
Confidence Intervals ◽  
Health Management ◽  
Diagnostic Technique ◽  
Turbine Engines ◽  
Data Sets ◽  
Gas Turbine Engines ◽  
Diagnostic Systems ◽  
Operating Characteristics ◽  
Hypothetical Data ◽  
Test Instance

The development and evaluation of new diagnostic systems requires statistically-based methods to measure performance. Various metrics are in use by developers and users of diagnostic systems. Current metrics practices are reviewed, including receiver operating characteristics, confusion matrices, Kappa coefficients and various entropy techniques. A set of metrics is then proposed for assessment of diverse gas path diagnostic systems. The use of bootstrap statistics to compare metric results is developed, and demonstrated for a set of hypothetical data sets with a range of relevant characteristics. The bootstrap technique allows the expected range of the metric to be assessed without assuming a probability distribution. A method is proposed to develop confidence intervals for the calculated metrics. The application of a confidence interval could prevent a good diagnostic technique being discarded because of a lower value metric in one test instance. The strengths and weaknesses of the various metrics with derived confidence intervals are discussed. Recommendations are made for further work.

Marine Operation of Gas Turbine Engines and Waterjet Pumps for Small Passenger Vessels

1979 ◽  
Author(s):  
S. M. Kowleski ◽  
C. D. Harrington
Keyword(s):  
Gas Turbine ◽  
San Francisco ◽  
High Speed ◽  
San Francisco Bay ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Golden Gate ◽  
Operational Problem ◽  
Golden Gate Bridge ◽  
Selection Of

This paper describes the planning, developmental, equipment selection and operational problem phases of the high-speed ferry system presently being operated on San Francisco Bay by the Golden Gate Bridge, Highway and Transportation District. The reasons for the selection of the vessel propulsion package consisting of gas turbine engines and waterjet pumps are discussed in some detail. Most importantly, the paper covers the problems experienced to date with this equipment in continuous marine operation.

scholarly journals The Basics of Powder Lubrication in High-Temperature Powder-Lubricated Dampers

1991 ◽  
Author(s):  
Hooshang Heshmat ◽  
James F. Walton
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Basic Mechanism ◽  
Test Facility ◽  
Experimental Program ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Powder Lubrication ◽  
Basic Features ◽  
Selection Of

The objective of this investigation is to develop a novel powder-lubricated rotor bearing system damper concept for use in high-temperature, high-speed rotating machinery such as advanced aircraft gas turbine engines. The approach discussed herein consists of replacing a conventional oil lubrication or frictional damper system with a powder lubrication system that uses the process particulates or externally-fed powder lubricant. Unlike previous work in this field, this approach is based on the postulate of the quasi-hydrodynamic nature of powder lubrication. This postulate is deduced from past observation and present verification that there are a number of basic features of powder flow in narrow interfaces that have the characteristic behavior of fluid film lubrication. In addition to corroborating the basic mechanism of powder lubrication, the conceptual and experimental work performed in this program provides guidelines for selection of the proper geometries, materials and powders suitable for this tribological process. The present investigation describes the fundamentals of quasi-hydrodynamic powder lubrication and defines the rationale underlying the design of the test facility. The performance and the results of the experimental program present conclusions reached regarding design requirements as well as the formulation of a proper model of quasi-hydrodynamic powder lubrication.

scholarly journals Generalized High Speed Simulation of Gas Turbine Engines

1990 ◽  
Author(s):  
Nanahisa Sugiyama
Keyword(s):  
Real Time ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Speed ◽  
Power Plants ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Jet Engines ◽  
Industrial Gas Turbine ◽  
High Degree

This paper describes a real-time or faster-than-real-time simulation of gas turbine engines, using an ultra high speed, multi-processor digital computer, designated the AD100. It is shown that the frame time is reduced significantly without any loss of fidelity of a simulation. The simulation program is aimed at a high degree of flexibility to allow changes in engine configuration. This makes it possible to simulate various types of gas turbine engines, including jet engines, gas turbines for vehicles and power plants, in real-time. Some simulation results for an intercooled-reheat type industrial gas turbine are shown.

Windage Heating of Air Passing Through Labyrinth Seals

1994 ◽  
Author(s):  
J. A. Millward ◽  
M. F. Edwards
Keyword(s):  
High Speed ◽  
Cooling System ◽  
Momentum Balance ◽  
Viscous Drag ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Secondary Cooling ◽  
Labyrinth Seals ◽  
Accurate Temperature ◽  
Cooling Air

The viscous drag on rotating components in gas turbine engines represents both a direct loss of power from the cycle and an input of heat into the secondary (cooling) air system. Hotter cooling air in turn means increased flow requirements. The effects of windage on performance are therefore compounded. To facilitate accurate temperature predictions of highly stressed components, information is needed on windage characteristics of all elements in the secondary cooling system. Much information is available in the literature for discs, cones, cylinders, bolts etc but little has been published on windage heating in high speed seals. Results are presented for experiments carried out (at representative non-dimensional conditions) on different designs of labyrinth seals. The results are compared with values calculated from the simple momentum balance theory suggested by McGreeham and Ko (1989) and with several values determined from CFD analysis.

MULTIPARAMETRIC DIAGNOSTICS OF GAS TURBINE ENGINES

2021 ◽  
Vol 156 (A2) ◽  
Author(s):  
J Sinay ◽  
A Tompos ◽  
M Puskar ◽  
V Petkova
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Technical Condition ◽  
Diagnostic Methods ◽  
Turbine Engines ◽  
Technical Diagnostics ◽  
Suitable Model ◽  
Gas Turbine Engines ◽  
Advantages And Disadvantages ◽  
The Matrix

This article addresses the issue of diagnostics and maintenance of Gas Turbine Engines which are located in high Speed Ferries, Cruisers, Frigates, Corvettes, etc. Assurance of reliable operation can be performed only by using correct diagnostic methods and procedures of monitoring the condition of the devices and by selecting the correct strategy of maintenance. The issue of monitoring the technical condition of Gas Turbine Engines is treated through multiparametric methods of technical diagnostics incorporated into predictive maintenance, which is a part of proactive maintenance. There are methods of vibrodiagnostics, thermography, tribology, borescopy and emissions measurement. Each of these methods has lots of advantages and disadvantages; therefore it is very important to ensure their correct combination for trouble-free operation of those important facilities. Their suitability at work is discussed in the matrix of diagnostic methods application and the PF chart. The output of the work is a proposal of a suitable model of maintenance control which uses multiparametric diagnostic methods for small and big Gas Turbine Engines and optimizes maintenance costs.

Analysis of High-Speed Cylindrical Roller Bearing With Flexible Rings Mounted in a Squeeze Film Damper

2007 ◽  
Author(s):  
Cyril Defaye ◽  
Daniel Nelias ◽  
Florence Bon
Keyword(s):  
Gas Turbine ◽  
Load Distribution ◽  
High Speed ◽  
Roller Bearing ◽  
Squeeze Film ◽  
Turbine Engines ◽  
Radial Clearance ◽  
Elastic Coupling ◽  
Gas Turbine Engines ◽  
Squeeze Film Damper

For high-precision mechanical systems such as gas-turbine engines, which operate under extreme conditions, it is particularly important to accurately predict the behavior of the mainshaft rolling bearings. This prediction includes, among others, the load distribution, stiffness and power dissipation. Although shaft speeds tend to increase, rings and shaft walls are becoming thinner due to size and weight constraints. Thus, bearing behavior is no longer independent of the housing and ring stiffness. Furthermore, since forty years, the use of squeeze film damper is largely widespread in gas-turbine engines to significantly reduce the vibratory levels. Due to the flexibility of the ring providing the interface between the roller bearing and the fluid film, it appears an elastic coupling which modifies the behavior of the bearing-squeeze film damper system. This paper presents first a squeeze film damper model with a flexible inner ring (i.e. outer ring of the roller bearing). An analytical stop model is introduced to reproduce the interference between the inner ring of the squeeze film damper and its housing. In a second part, an elastic coupling between the presented squeeze film damper model and an existing roller bearing model is proposed. Finally, the results presented show that this coupling has a first order influence on the behavior of the bearing-squeeze film damper system. It is also shown that the coupling between a roller bearing and a squeeze film damper when linked by a flexible ring introduces a dissymmetry of the load distribution with respect to the applied load direction. Moreover, in certain cases, the position of the bearing in its housing can reach eccentricities larger than the radial clearance of the squeeze film damper.

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